Language disorders may have psychological and physiological etiologies. For example, the autism spectrum disorders (autism, pervasive developmental disorder, and acquired epileptic aphasia) are associated with language, behavior and social disability. These disabilities are believed to be a manifestation of electrographic and other functional disturbances in one or more language regions of the brain, as well as regions mediating behavior and social interaction skills. Persons with autism and pervasive developmental disorders, as well as acquired epileptic aphasias such as Landau-Kleffner, have a high prevalence of epilepsy and of epileptiform abnormalities.
Autism (sometimes called “classical autism”) is the most common condition in a group of developmental disorders known as the autism spectrum disorders. The Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) defines autistic disorder as a syndrome with qualitative impairments in social interaction, communication, and restricted and stereotyped patterns of behavior, interests and activities. Autism varies widely in its severity and symptoms and may go unrecognized, especially in mildly affected children, or when masked by more debilitating handicaps. Symptoms typically begin before age 3 and may include problems using and understanding language; difficulty relating to people, objects, and events; unusual play with toys and other objects; difficulty with changes in routine or familiar surroundings, and repetitive body movements or behavior patterns.
Other autism spectrum disorders are characterized by delays in the development of socialization and communication skills. Asperger syndrome is an autism spectrum disorder characterized by a greater or lesser degree of impairment in language and communication skills, as well as repetitive or restrictive patterns of thought and behavior. Other autism spectrum disorders include Rett syndrome, childhood disintegrative disorder and pervasive developmental disorder not otherwise specified (usually referred to as PDD-NOS).
Landau-Kleffner syndrome is the best-described syndrome of acquired epileptic aphasia. This condition affects children, usually between the ages of 3 and 7, who previously had no developmental, language, or interactional difficulties. Subject's typically experience a rather abrupt loss of language comprehension and expression, usually coincident with the onset of seizures and a profoundly abnormal sleep EEG. Electrographic status epilepticus (prolonged seizures) in sleep, or continuous spike-wave in slow-wave sleep is typical in acquired epileptic aphasia and in the Landau Kleffner Syndrome (Trevathan E., “Seizures and epilepsy among children with language regression and autistic spectrum disorders.” J. Child Neurol. 2004; 19(S1):S49-57). The cause for the aphasia in Landau-Kleffner syndrome is uncertain. The seizures and the aphasia are believed to reflect abnormal brain functioning or the aphasia may be a consequence of the seizure discharges.
Clinically evident seizures, as well as subclinical epileptiform discharges and epileptiform electrographic abnormalities, may exacerbate or even cause the cognitive, language and behavior disorders characterizing the autism spectrum disorders and acquired epileptic aphasias. As many as 75% of children with autism have electroencephalogram (EEG) abnormalities and up to 46% have clinical seizures (Hughes J R, Melyn M., “EEG and seizures in autistic children and adolescents: further findings with therapeutic implications.” Clin. EEG Neurosci. 2005; 36(1): 15-20; Hrdlicka M., Komarck V., Propper L., Kulisck R., Zumrova A., Faladova L., Havlociocova M., Sedlacek Z., Blainy M., Urbanek T., “Not EEG abnormalities but epilepsy is associated with autistic regression and mental functioning in childhood autism.” Eur. Child Adolesc. Psychiatry 2004; 13(4):209-213; Tharp B R, “Epileptic encephalopathies and their relationship to developmental disorders: do spikes cause autism?” Ment. Retard. Dev. Disabil. Res. Rev. 2004:10(2):132-134). The prevalence of epilepsy and epileptiform abnormalities in persons with autism spectrum disorders is highest in those with moderate to severe retardation, motor deficits, severe receptive language deficits (Tuchman R., Rapin I., “Epilepsy in autism.” Lancet Neurol. 2002; 1 (6):352-358), early language regression (Trevathan E., “Seizures and epilepsy among children with language regression and autistic spectrum disorders.” J. Child Neurol. 2004; 19(S1):S49-57) or abnormal development during the first year of life. Epileptic seizures are also associated with progressive regression in children with autism (Rossi P. G., Parmeggiani A., Bach V., Santucci M., Visconti P., “EEG features and epilepsy in patients with autism.” Brain Dev. 1995; 17(3):169-174).
Currently, there is no cure for autism spectrum disorders or acquired epileptic aphasias. Therapies and behavioral interventions are designed to remedy specific symptoms. Treatment plans coordinate therapies and interventions that target social interaction, verbal and nonverbal communication, and obsessive or repetitive routines and interests. Medications are used to address specific behavioral problems. Furthermore, we are not aware of any randomized clinical trials of treatments for autistic language regression. Some persons with autism improve cognitively when treated with antiepileptic drugs (AEDs). However, the potential for cognitive side effects limits AED use.
As an alternative or adjunct to medication, surgical interventions have also been used as treatments. For example, vagus nerve stimulation (VNS) and multiple subpial transections, or cortical resection, have been performed to treat autism spectrum disorders. The impact of VNS on quality of life and alertness in 6 children with Landau-Kleffner Syndrome and 59 persons with autism was examined utilizing a retrospective subject outcome registry (Park Y. D., “The effects of vagus nerve stimulation therapy on patients with intractable seizures and either Landau-Kleffner syndrome or autism.” Epilepsy Behav. 2003; 4(3):286-290). Fifty-eight percent of the subjects with Landau-Kleffner Syndrome and 78% of the subjects with autism reported improved quality of life and enhanced alertness. It is not possible to differentiate whether these effects were related to reductions in seizures or to an independent mood effect given this study design.
Other surgical treatments include subpial transection. For example, a small number of children with Landau-Kleffner syndrome who have not responded to antiepileptic medications have been treated with subpial transection (Nass R, Neville B. G., Harkness W. F., Cross J. H., Cass H. C., Burch V. C., Lees J. A., Taylor S. C., “Surgical treatment of severe autistic regression in childhood epilepsy.” Pediatr. Neurol. 1997; 16(2): 137-140). This procedure severs interneuronal connections perpendicular to the trajectory of the cortical neuron. The procedure is performed in the language area of the frontal lobe coincident with the maximal electroencephalographic abnormalities. The procedure is thought to inhibit the propensity for abnormal electroencephalographic discharges to propagate to adjacent neurons while preserving fiber tracts subserving motor and sensory function.
Thus, there is a need for treatments and systems for treating language, behavioral and/or social disorders, and particularly those related to autism, pervasive developmental disorders, and acquired epileptic aphasias. A system and method of using such a system could benefit individuals with autism spectrum disorders and acquired epileptic aphasias, for which there is no effective treatment.